The frequency band for some telecommunications signal frequencies (e.g. “4G”) may abut or reside closely with a radar signal frequency (e.g. the “S-Band”—from 2 GHz to 4 GHz). A narrow buffer zone typically exists in the frequency spectrum separating telecommunications signal frequency band from the radar signal frequency band. This aims to avoid interference of telecommunications signals with radar operations. The distribution of such neighbouring bands is shown schematically in FIG. 1.
However, circumstances can arise in which telecommunications signals may appear within, or may migrate to, frequencies falling within the radar band adjacent to it. A spill-over can occur from the spectral content of the telecommunications signal frequency band into the radar band. Radar receivers may pick up interference from the low-level spectral content of a telecoms signal that can extend for up to one quarter of the way into a radar band. These interfere with radar operations and are detrimental to safety, especially with respect to airport radar systems etc.
The invention aims to address this.